1. Field of the Invention
The present invention relates to a control board for a controller.
2. Description of the Related Art
FIG. 8 is a view showing a conventional control board for a controller.
In FIG. 8, reference numeral 51 denotes a control board; 52 a printed board; 53 a terminal stand for connecting an external signal; 54 an input circuit section; 55 an output circuit section; and 56 a control section. The conventional control board 51 integrates the terminal stand 53, input circuit section 54, output circuit section 55 and control section 56 on the printed board 52.
The input circuit section 54 converts an external signal into a control signal processable by the control section 56 through an isolation means (not shown). The output circuit section 55 converts the control signal outputted from the control section 56 into the external signal through the isolation means (not shown).
FIGS. 9A and 9B are views showing the terminal stand mounted on the conventional control board for a controller. FIG. 9A shows a terminal stand for a screw terminal which has been used generally in Japan, and FIG. 9B shows a terminal stand for a dipping terminal which has been generally used in Europe.
The input/output section such as the input circuit 54 and output circuit section 55 has also two kinds of input/output specifications including a sink specification and a source specification.
FIG. 10 shows a conventional input/output circuit section in a sink specification. FIG. 11 shows a conventional input/output circuit section in a source specification.
In FIG. 10, inputs Nos. 1 to n denote input terminals for external signals; CG a common terminal for an external signal; outputs No. 1 to n output terminals for external signals; CCG an external output common terminal; 52a a printed board; 53 a terminal stand; 54a an input circuit section in a sink specification; 55a an output circuit section in the sink specification; 61 a resistor; 62 a photo-coupler; 17 a resister; 64 an npn transistor; 65 a resistor; 66 a photocoupler; and 67 a resistor.
The inputs Nos. 1 to n and the outputs Nos. 1 to n have the same function, respectively. Their functions will be explained representatively for the input No. n and output No. n.
The input No. n is connected to the resistor 61 whose one terminal is connected to the cathode of an input LED of the photocoupler 62. When an input signal is supplied (the input No. n and CG are short-circuited) between the input No. n and CG, a current starts to flow from the input No. n to turn on the photocoupler 62.
The output No. n is connected to the collector of the npn transistor 64 and the output collector of the photocoupler 66. The external output common terminal CCG is connected to the emitter of the npn transistor 64 and the resistor 65. The emitter of the photocoupler 66 is connected to the one terminal of the resistor 65 and the base of the npn transistor 64.
In FIG. 11, reference symbol P24 denotes a 24 V terminal of an external signal; input No. 1 to n input terminals for external signals; P24G an external output 24 V terminal; outputs Nos. 1 to n output terminals for external signals; 52b a printed board; 53 a terminal stand; 54b an input circuit section in a source specification; 55b an output circuit section in a source spefication; 71 a resistor; 72 a photocoupler; 73 a resistor; 74 a pnp transistor; 75 a resistor; 76 a photocoupler; and 77 a resistor.
The inputs Nos. 1 to n and the outputs Nos. 1 to n have the same function, respectively. Their functions will be explained representatively for the input No. n and output No. n.
The input No. n is connected to the anode of an input LED of the photocoupler 72. The cathode of the input LED is connected to the resistor 71. The one terminal of the resistor 71 is connected to the 24 V common terminal. When the external signal is supplied between the input No. n and P24 (the input No. n and P24 are short-circuited), a current flows into the input No. n to turn on the photocoupler 72 so that the external signal is transferred.
The output No. n is connected to the collector of the npn transistor 74 and the output emitter of the photocoupler 76. The external output 24 V terminal P24G is connected to the emitter of the pnp transistor 74 and the resistor 75. The one terminal of the resistor 75 is connected to the output collector of the photocoupler 76 and the base of the pnp transistor 74.
Although the terminals used generally in each country are different (screw terminal in Japan and dipping terminal in Europe), the terminal control board integrates the terminal stand with the input circuit section, output circuit section and control section on the printed board so that a user cannot choose the terminal stand independently from the other parts of the board. For this reason, where the control appliance made in Japan is to be used in Europe, because the terminal stand is dedicated to the screw terminal, the crimping contact is not used and a less familiar contact must be prepared and wired.
Where a manufacturer assembles the control board, even with advancement of plane-mounting of components on the control board, because the terminal stand and the relay are DIP components, plane-mounted components are attached by an automatic insertion machine and thereafter the terminal stand and relay must be attached manually, thus increasing the number of steps.
While the control section is common, the input/output specification includes two kinds of specifications of sink specification and source specification. Therefore, the control boards dedicated to the sink specification and source specification, respectively must be prepared.
Further, the standard combination of the terminal stand and input/output specification in each country is the combination of screw terminal and sink specification in Japan and that of dipping terminal and source specification in Europe. For this reason, plural kinds of control boards with different combinations (e.g. combination of screw terminal and sink specification and that of dipping terminal and source terminal) must be prepared.
Where the initial value of the program in the control section must be set in accordance with the circumstances of power source in each country, plural kinds of control boards corresponding to the circumstances of power source (e.g. control boards with the initial values stored for domestic use and Europe use, respectively) must be prepared.